Disc player apparatus having a signal processing circuit which produces a reproduction clock synchronism with a reproduced signal

Abstract

A disc reproduction apparatus, configured so that a voltage-controlled oscillator is used as a device of giving a reference frequency to an analog phase-locked loop circuit, a control voltage based on a speed error of the rotational speed of a spindle with respect to the reference speed is given to this voltage-controlled oscillator by a rotational speed counting circuit, and a reference clock is produced in the analog phase-locked loop circuit based on the oscillation frequency given by this voltage-controlled oscillator and, at the same time, the reproduction clock PLLCK is produced by the digital phase-locked loop circuit based on this reference clock, whereby the operation becomes stable with respect to rotational outer disturbances and high speed access is enabled.

What is claimed is: 
     
       1. A signal processing circuit of a disc reproduction apparatus which produces a reproduction clock in synchronization with a signal reproduced from a disc and performs signal processing with respect to said reproduced signal based on said reproduction clock, comprising: a rotational speed counting means for detecting a rotational speed of a spindle based on said reproduced signal and producing a speed error as a control signal in accordance with the detected rotational speed and a reference speed;   an oscillation means whose oscillation frequency changes in accordance with said control signal;   a first phase-locked loop circuit which produces a reference clock of a predetermined frequency based on the oscillation frequency of said oscillation means; and   a second phase-locked loop circuit which produces said reproduction clock based on said reference clock, detects a frequency error and a phase error of said reproduced signal with respect to said reproduction clock, and controls a frequency and a phase of said reproduction clock based on that frequency error and phase error.   
     
     
       2. A disc reproduction apparatus as set forth in claim 1, wherein said rotational speed counting means has a first detection means for detecting a speed difference of the rotational speed of the spindle with respect to the reference speed; a second detection means for detecting a cycle difference of the cycle of said reproduced signal with respect to a reference cycle; and a changeover means for outputting the speed difference detected by said first detection means as said control signal and then outputting the cycle difference detected by said second detection means as said control signal. 
     
     
       3. A disc reproduction apparatus which produces a reproduction clock in synchronization with a signal reproduced from a disc and performs a signal processing with respect to said reproduced signal based on said reproduction clock, comprising: a rotational speed counting means for detecting a rotational speed of a spindle based on said reproduced signal and producing a speed error as a control signal in accordance with the rotational speed of the spindle and a reference speed;   a filter means whose cut-off frequency is variable in accordance with a changeover control signal and which extracts only a predetermined frequency range of said control signal by a related cut-off frequency and outputs the same;   an oscillation means whose oscillation frequency changes in accordance with a control signal output from said filter means;   a first phase-locked loop circuit which produces a reference oscillation clock of a predetermined frequency based on the oscillation frequency of said oscillation means;   a second phase-locked loop circuit which produces said reproduction clock based on said reference oscillation clock, detects a frequency error and a phase error of said reproduced signal with respect to said reproduction clock, and controls a frequency and a phase of said reproduction clock based on that frequency error and phase error;   an acceleration detection means for receiving said oscillation output and reference clock and detecting roll acceleration; and   a control means for outputting said changeover control signal in accordance with a result of a comparison between said detected acceleration and a preliminarily set acceleration to said filter means.   
     
     
       4. a disc reproduction apparatus as set forth in claim 3, wherein said rotational speed counting means has a first detection means for detecting a speed difference of the rotational speed of the spindle with respect to the reference speed; a second detection means for detecting a cycle difference of a period of said reproduced signal with respect to a reference period; and a changeover means for outputting speed difference detected by said first detection means as said control signal and then outputting the period difference detected by said second detection means as said control signal. 
     
     
       5. A disc reproduction apparatus as set forth in claim 3, wherein said first phase-locked loop circuit has a first frequency division means for dividing said oscillation output with a variable frequency division ratio; a second frequency division means for dividing said reference oscillation clock with a variable frequency division ratio; and a phase comparison means for detecting a phase difference of the respective divided outputs of said first and second frequency division means. 
     
     
       6. A disc reproduction apparatus as set forth in claim 3, wherein said acceleration detection means has a cycle counting means which counts the cycle of the oscillation output of said oscillation means in said reference clock; a speed change calculation means for finding the speed change based on the result of counting of said cycle counting means; and a comparison means for comparing the magnitude of the speed change with the preliminarily set value and outputs the result thereof to said control means. 
     
     
       7. A disc reproduction apparatus as set forth in claim 3, wherein said control means produces said changeover control signal which raises the cut-off frequency of said filter means where the detected acceleration is larger than the set acceleration and lowers the cut-off frequency of said filter means where the detected acceleration is smaller than the set acceleration.